Visualizing the A1c

Most of us have heard of the hemoglobin A1c test. That’s what measures our average blood glucose levels over the past several months. But how many of us really understand what the hemoglobin A1c is?

To help us understand, Casey Steffen , who has type 1 diabetes, has come up with rubber models of both the hemoglobin molecule and the hemoglobin A1c. There’s nothing like seeing something in 3D to remember what it is.

In these models, the red represents the heme groups. These are small iron-containing parts of hemoglobin that are responsible for carrying oxygen to cells and carrying carbon dioxide back to the lungs to be exhaled. Hemoglobin consists of four protein subunits and four heme groups.

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The blue represents sugar molecules bound to the protein.

The model of hemoglobin shows it with zero sugars attached. Actually, no one has an A1c level of zero, because everyone has some glucose in the blood. Normal A1c in a young person might be around 4. So a more realistic model of the “control” hemoglobin might include one or two glucose molecules. Still, it shows you what hemoglobin is without any sugar.

The model of hemoglobin A1c shows the hemoglobin if your glucose levels were so high that every possible site had a glucose attached, according to Steffen.

Hemoglobin isn’t the only protein that binds glucose; it’s just a way of estimating how much glucose is circulating in your blood. And you can imagine what would happen if the enzymes in your body, or insulin or other protein hormones, or the LDL or insulin receptors bound similar amounts of glucose. Their activity would likely be altered, and this would cause problems.

If you’re interested in reading more about the producer of these models, Mike Hoskins of Diabetes Mine has written a good article about the work.